It is well known that LEDs give off heat during operation and that light output from an LED decreases with increasing LED die junction temperature. Accordingly, there is a well-recognized need for reducing LED die junction temperatures in LED flashlights to increase performance.
In designing a flashlight with an LED, there are two main battery sources available for powering one or more LEDs used as light sources—rechargeable and non-rechargeable batteries; increasing the number of batteries will increase the available voltage which can increase LED driver circuit efficiency.
Alkaline batteries have provided power to flashlights for decades. A general description of the construction of alkaline batteries is described in the prior art, an example of which is the article found at http://www.electrical4u.com/alkaline-batteries, as well as a technical bulletin about Duracell® batteries found at http://ww2.duracell.com/en-US/Global-Technical-Content-Library/Technical-Bulletins.jspx, both of which are incorporated by reference herein, from which FIG. 1 and the following description of such construction is obtained. The body of a battery, generally designated as 100, is made of a hollow steel can 102 comprised of an outer cylindrical wall 102OC, a top surface 102TC and a bottom surface 102BC. Can 102 contains all materials of the battery. A positive cap with a nipple 103 of battery 100 is projected from the top of can 102. A manganese dioxide cathode powder mix 104 is pressed against the inner steel wall of can 102 so that the steel case of the can becomes the cathode current collector and serves as the positive terminal of the cell. The inner surface of the thick layer of cathode mixture is covered with a porous separator 105 which isolates the electrodes of the battery. The central space, inside separator 105, is filled by a zinc anode powder 106. The porous nature of the anode, cathode, and separator materials allows them to be thoroughly saturated with the alkaline electrolyte solution. A metallic pin 107 is welded to the external anode cap 111 and extends through a plastic cap or grommet 109 into the center of the anode powder mix maintaining intimate contact. This pin is called a negative collector pin or an anode current collector. Plastic cap or grommet 109 is sealed to the steel can 102 by means of radial crimping pressure and a sealant. Anode cap 111 is electrically isolated from the positive cell case 102 with an insulator 110. A vent mechanism 112 is incorporated into the plastic grommet 109 to protect against cell rupture. An outer insulative wrapping 102W is also commonly applied to can 102 which is also used to contain printed material, such as trademarks and trade dress of the battery manufacturer.
However, despite the fact that alkaline batteries have been used in flashlights for decades, there has been a well-known problem that batteries can leak battery corrosive electrolyte over time, causing problems related to cleaning such leaks and sometimes ruining a flashlight in which the leak occurs. Accordingly, there is a long-felt need for a way to minimize battery corrosive electrolyte leaks in flashlights.
The present invention discloses and teaches a much improved LED flashlight, preferably with an outer metallic flashlight housing or barrel, which achieves superior performance through improved heat control of LED die junction temperature via an improved heatsink assembly while also minimizing battery corrosive electrolyte leaks, thus increasing reliability.